Technical Service Manual

Specifications

For the basic operation instructions, please refer to the instruction manual attached with each unit.

Water Circuit and Function Description

Water Circuit Scheme

The water circuit diagram illustrates the flow of water within the dishwasher. It shows the 'Inlet water route' (indicated by magenta arrows), 'Drain water route' (indicated by blue arrows), and 'Cycle water route' (indicated by cyan arrows). Key components include the inlet hose, air breaker, water softener, top, upper, and lower sprayer arms, sump, drain hose, inlet valve, washing pump, and drain pump. Note: Diagrams may vary slightly for models with common inlet hoses or Aquastop hoses.

Function Description

Process of Water Inlet (indicated by magenta route)

In this process, the regeneration water route is cut off, and the main water route is open. Water in the main water route is softened when passing through the softener and then enters the tub. During this phase, some inlet water is stored in the air breaker for regenerating water.

Process of Cycle Washing (indicated by blue route)

Cycle washing action is driven by the washing pump motor. Water gains power as it passes through the working washing pump, then it is pumped into the spray arms, passes through the spray arm nozzles, over the dishes, into the sump, where it connects to the washing pump, and proceeds to the next water cycle.

Theory of Parts

Location

An exploded view of the dishwasher shows the location of major components. These include the Air Breaker, Washing Pump, Heater, Pressure Switch, Softener, Drain Pump, Sump, and Main PCB. Note: Exploded views and part lists may differ between models; refer to the latest version provided.

PCB

The Printed Circuit Board (PCB) is the control center of the dishwasher. It receives and processes signals from components, sends commands to components, and handles feedback information.

Access PCB

The PCB can be removed from its protecting box located in the bottom of the machine. The steps involve:

1. Disconnect power supply.
2. Remove cutlery basket, main basket, and filter system.
3. Remove screws fixing the protecting box and open its cap.
4. Remove screws securing the PCB to the protecting box.
5. Disconnect the connector from the PCB.
6. Remove the PCB.
7. Reverse the above procedure to install.

PCB View and Description

A detailed map of the PCB (applicable to model 7601) shows various components and their connections. A table lists the marked components (NO., Mark) and their functions.

Minor differences in component placement may exist between models, but the markings on the PCB retain their meaning.

Inlet Valve

Location and Appearance

The inlet valve is located at the bottom of the machine. Its appearance shows terminals, a connection for the inlet water hose, a connection to the air breaker, and an electric coil inside.

Work Principle

The inlet valve is an electromagnetic valve that controls water entry. It is normally closed and opens when the appliance requires water, signaled by the controller. It consists of an electric coil, valve body, valve pole, and filter.

Defeat Points

• Valve coil broken: Valve cannot open (E1 error).
• Filter jammed: Water cannot enter (E1 error).
• Connector loose: Valve cannot open (E1 error).
• Valve pole rusted or locked by dreg: Valve cannot open or close (E1 or E4 error).

Technical Data

Access Inlet Valve

1. Disconnect power.
2. Remove the water inlet hose (caution: residual water may drip).
3. Remove the cover of the bottom board.
4. Disconnect the 2 terminal lugs from the inlet valve.
5. Pull out the valve while rotating it counter-clockwise to remove it.
6. Remove the clamp and disconnect the inlet hose (to air breaker) from the water valve.
7. Reverse the above procedures to install.

Inspect Inlet Valve

Check Electric Part

Open the protecting box and take out the PCB. With the door closed, unplug CON3 and ACN wires. Measure resistance between the blue wire (EV1) and the blue wire (ACN) using a multimeter. Normal resistance is approximately 4.4kΩ to 4.8kΩ. If incorrect, the valve coil may be broken or the connector loose. Check connection first, then replace the valve if necessary. If resistance is OK, inspect the valve body.

Check Machine Part

1. If the electric part is OK, check the machine part.
2. Check the valve filter; clear residues if blocked.
3. If the filter is clear but water doesn't enter, check if the valve can act. If not, replace the valve.
4. If water continues to enter, replace the valve.

Drain Pump

Location and Work Principle

The drain pump is integrated into the sump. It consists of an electrical motor, impeller, inlet, and outlet. It is driven by a permanent magnet synchronous motor, designed for easy starting due to the low inertia of the rotor.

Defeat Points

• Motor coil broken: Drain pump cannot work (E1 error).
• Weak motor rotor magnetism: Drain pump cannot work (E1 error).
• Connector loose: Drain pump cannot work (E1 error).
• Rotor locked by residues: Drain pump cannot work (E1 error).
• Drain pump assembly rack loose: Causes noise.
• Non-return valve bad: Causes residual water.

Explanatory Notes: A drain pump failure can lead to an E1 error because if water is not drained, the pressure switch may cut off the inlet valve in the next cycle, preventing water entry.

Technical Data

Access Drain Pump

1. Drain water from the dishwasher and disconnect power. (Ensure all water is removed to prevent floor wetting.)
2. Remove the cover of the bottom board, carefully releasing top, left, and right hooks.
3. Label and disconnect the two terminal lugs from the drain pump.
4. Rotate the drain pump counter-clockwise to remove it.
5. Reverse the above procedure to install.

Inspect Drain Pump

Check Electric Part

Open the protecting box and take out the PCB. With the door closed, unplug CON3 and ACN wires. Measure resistance between the red wire (PS) and blue wire (ACN). Normal resistance is about 220Ω to 250Ω. If incorrect, the pump coil may be broken or the connector loose. Check connection first, then replace the drain pump. If resistance is OK but it doesn't work, the magnetism may be too weak; replace the drain pump.

Check Machine Part

1. If the electric part is OK, check the machine part.
2. Remove the bottom board.
3. If the non-return valve is wrongly assembled, residual water will remain. Re-assemble the non-return valve.
4. If the drain pump works but drains little or no water, check the drain hose or drain body.

Heater

Location and Work Principle

The heater is located at the bottom of the machine. The work principle involves a heater element, a fuse, and a pressure switch in a circuit.

Technical Data

Defeat Points

• Heater coil broken: Heater cannot work (E3 error).
• Fuse active: Heater cannot work (E3 error).
• Connector loose: Heater cannot work (E3 error).

Access Heater

1. Drain off water and disconnect power. (Ensure all water is removed.)
2. Remove the bottom board.
3. Label and disconnect the terminals.
4. Remove the 2 clamps for fixing pump hoses. (Caution: Clamps are easily damaged and cannot be reused; replace with a new universal clamp.)
5. Rotate the upper pump counter-clockwise to take it off.
6. Reverse above procedures to install.

Inspect Heater

Remove the bottom board. With the door closed, use a multimeter to measure resistance between the heater terminals. The resistance should be about 27Ω to 30Ω. If incorrect, the heater coil or thermostat is broken; replace the heating element or thermostat.

Washing Pump

Location and Work Principle

The washing pump is located at the bottom of the machine. It is an asynchronous motor with a capacitor, consisting of a silicon steel stack and two coils: main coil (M) and assistant coil (A).

Defeat Points

• Motor coil broken: Wash pump cannot work (E3 error).
• Weak motor rotor capacitor: Washing pump cannot start, may produce electromagnetism noise. Thermal protector may activate (E3 error).
• Connector loose: Wash pump cannot work (E3 error).
• Rotor locked by residues: Wash pump cannot work (E3 error).
• Drain pump assembly bracket loose: Causes noise.
• Machine unused for a long time: Wash pump may not start.

Technical Data (Model YXW50-2E)

Access Washing Pump

1. Disconnect power.
2. Remove bottom board.
3. Label and disconnect the terminals.
4. Remove the 2 clamps for fixing pump hoses. (Caution: Clamps are easily damaged and cannot be reused; replace with a new universal clamp.)
5. Rotate the upper pump counter-clockwise to take it off.
6. Remove the screw fixing the impeller to the pump.
7. Remove the 2 screws fixing the lower pump to the motor.
8. Reverse above procedures to install.

Inspect Washing Pump

Check Electric Part

Open the control panel and take out the PCB. With the door closed, unplug CON1 and CON2. Test resistance between ML-H and ACN (normal: 100Ω to 130Ω) and between ML-H and ML-L (normal: 35Ω to 45Ω). If resistance is incorrect, the pump coil may be broken or the connector loose; check connection first, then replace the pump. If resistance is OK but it doesn't work, the capacitor may be weak; replace the capacitor.

Check Machine Part

1. If the electric part is OK, check the machine part.
2. Remove the bottom board.
3. Check the pump assembly bracket; tighten if loose to prevent noise.
4. If the wash pump cannot start and the machine hasn't been used for long, the seal element may be bonded.
5. If the drain pump works but drains little or no water, check the vane wheel.

Pressure Switch

Work Principle

The pressure switch consists of a moving diaphragm and disc that activate a change-over contact. It can be calibrated to trip and reset at desired pressure levels and is primarily used to control water levels in appliances. It may also provide flood protection.

Images show the front and back views of the pressure switch, with terminals labeled 1-COM, 2-NC, and 3-NO.

NTC (Negative Temperature Coefficient Thermistor)

Location and Work Principle

The NTC thermistor is integrated into the sump and is used for measuring the water temperature in the tub.

Access NTC

1. Remove the bottom board.
2. Remove two screws securing the NTC to the sump.
3. Take out the NTC.
4. Reverse the above procedure to install.

Inspect NTC

Open the protecting box and take out the PCB. With the door closed, unplug the RE connector. Use a multimeter to test resistance between the RE and GND wires. The normal resistance varies with temperature as shown in the NTC resistance table. If the resistance is incorrect, the NTC circuit has a problem. Check the connection first, then replace the NTC if the issue persists.

NTC Resistance Table

Flowmeter

Location and Work Principle

The flowmeter is integrated into the Air Breaker. Its function is to measure the amount of water entering the appliance. It consists of an impeller, a tongue tube, and a terminal. When water passes through, it rotates a magnetic impeller, which the tongue tube senses to send electronic pulses.

Access Flowmeter

1. Remove the baseboard, top panel, and left side panel.
2. Remove the plastic nut inside the tub that secures the air breaker to the tub. (If the flowmeter fails, the air breaker assembly must be replaced.)
3. Disconnect the wire and remove the clamp fastening the hose to the air breaker.
4. Take out the air breaker.
5. Reverse the above procedure to install.

Inspect Flowmeter

Open the protecting box and take out the PCB. With the door closed, unplug the CON2 wire. Use a multimeter's diode setting to test between the black wire (FM) and blue wire (GND) to confirm if electrical pulses are sent out while water passes through the flowmeter. Continuous pulses will produce a continuous sound. No pulses indicate a flowmeter circuit problem. Check connections first, then replace the air breaker assembly if the issue persists.

Safety Hose

Location and Work Principle

There are two types of Safety Hose: mechanical Aquastop hose and electronic Aquastop hose, each with different principles and assembly modes.

Images show the mechanical Aquastop hose (with two layers and foaming material inside) and the electronic Aquastop hose (with two layers, electromagnetism valve inside, and connection to air breaker).

Mechanical Aquastop safety hose: Has two layers. If water leaks into the space between them, the foaming material expands and locks the hose, potentially triggering an E1 alarm.

Electronic Aquastop safety hose: Also has two layers. If water leaks onto the bottom tray, a flooding pressure switch activates, the electromagnetic valve on the hose cuts off the water, and the machine may trigger an E4 alarm.

Access Safety Hose

1. Remove the baseboard, side baseboard, top panel, and left side panel.
2. Remove the clamp, cut the bound belt, and disconnect the wire connector. Then, the inlet hose can be pulled out.
3. Reverse the above procedure to assemble.

Inspect Safety Hose

Electronic Aquastop Hose

Open the protecting box and take out the PCB. With the door closed, unplug CON3 and ACN wires. Use a multimeter's Ω shelf to measure resistance between the blue wire (EV1) and blue wire (ACN). Open circuit and short circuit are both incorrect. If the measured resistance is incorrect, the valve coil is broken or the connector is loose. Check connection first, then replace the safety hose.

Mechanical Aquastop Hose

Moisture absorption by the foaming material in the mechanical device can cause a self-lock fault (inability to fill water), which is non-resettable.

Diverter Valve

Work Principle

The diverter valve, also known as an alternating flow control valve, controls water flow between the upper and lower spray arms. It can also stop water flow to the upper spray arm on models with a half-load feature.

A hydraulic scheme shows the diverter valve's connection to the top spray arm, bottom spray arm, motorized diverter valve, and pump.

Access Diverter Valve

1. Disconnect power.
2. Remove bottom board.
3. Label and disconnect the 4 terminals.
4. Remove 1 screw fastening the diverter valve to the sump.
5. Rotate the diverter valve counter-clockwise to take it off.
6. Reverse the above procedure to install.

Note: This page is only for models with a diverter valve.

Test Program

This program is designed for technicians to check component operation and diagnose malfunctions.

How to Activate Test Program

To activate the test program, with the door opened and within 60 seconds after power on, hold down the 'Rapid' button and press the 'POWER' button until the machine enters 'Test Rapid'. The appliance will pause and stand by (step 00). Then, close the door to start the Test Rapid. During test program running, you can press the 'Rapid' button to jump to the next step (except for the inlet valve step).

Note: 1. The activation method may differ slightly between models. 2. Switch off the unit from the wall, then switch on before following the instructions above to activate the test cycle.

Procedure

Procedure of Test Program (for models controlling water filling by flowmeter)

Error Code

How to Know Which Error Code Has Occurred

Refer to the 'Test Program Operation' table. For example, if error 7 has happened, the buzzer will alarm for 30 seconds, and the ECO, 90min, and Rapid indicators will flash simultaneously. Other error alarms can be deduced similarly.

Indicator lights for ECO, 90Min, Rapid, binary numeral, and decimal numeral are shown.

The table shows the corresponding relation between indicator combination and error code. Most models follow this regulation.

Attention

Priority level of E4 is the highest. E4 operation is valid only after other error operations have completed. When E4 operation is done, all others are invalid. In test program, E1, E3, E4, E6, E7, and E8 are valid. Note: E8 is valid for models equipped with a diverter valve (alternative washing function).

How Does the Appliance React When Error Code Occurred

E1 Water Filling Exceed Pre-set Time

If the inlet valve is open for 4 minutes but the water quantity hasn't reached the desired value, E1 occurs. The drain pump runs until the flowmeter is motionless for 2 minutes, and all other components stop. The buzzer alarms for 30 seconds, and error 1 is shown.

E3 Heating Exceed Pre-set Time

If the heating element works for 60 minutes but the water temperature detected by NTC hasn't reached the desired value, E3 occurs. The drain pump runs until the flowmeter is motionless for 2 minutes, and all other components stop. The buzzer alarms for 30 seconds, and error 3 is shown.

E4 Overflow

If the overflow micro-switch activates and stays active for over 2 seconds, E4 occurs. The drain pump runs until the flowmeter is motionless for 2 minutes, and all other components stop. The buzzer alarms for 30 seconds, and error 4 is shown. Note: E4 has the highest priority.

E6 Open-Circuit Failure of Thermistor

In test program, if an open-circuit failure of the thermistor is detected, E6 occurs. The drain pump runs until the flowmeter is motionless for 2 minutes, and all other components stop. The buzzer alarms for 30 seconds, and error 6 is shown.

E7 Short-Circuit Failure of Thermistor

In test program, if a short-circuit failure of the thermistor is detected, E7 occurs. The drain pump runs until the flowmeter is motionless for 2 minutes, and all other components stop. The buzzer alarms for 30 seconds, and error 7 is shown.

E8 Diverter Valve Fault

For models with a diverter valve: If the machine doesn't detect the diverter valve's feeding signal for 15 seconds or its accurate positioning within 60 seconds during test program or washing, E8 occurs. The diverter valve stops, and E8 is set off after the program ends. When E8 occurs, the drain pump runs until the flowmeter is motionless for 2 minutes, and all other components stop. The buzzer alarms for 30 seconds, and the error code is shown.

Inspection (Troubleshooting Flowcharts)

E1 Tree

This flowchart guides troubleshooting for 'Longer inlet time' (E1 code). It starts by checking for water in the tub, then proceeds through checks of the AQUASTOP hose, tap, inlet hose, inlet valve circuit, pressure switch, flowmeter, hydraulic pressure, and drain hose. If issues persist, PCB malfunction is suspected.

E3 Tree

This flowchart guides troubleshooting for 'Longer heating time' (E3 code). It involves checking water temperature, over-heat proof micro-switch, filter status, heater circuit, washing pump circuit, and NTC circuit. If problems persist, replacement of the Inlet Valve, Washing Pump, or NTC may be required.

E4 Tree

This flowchart addresses 'Overflow' (E4 code). It checks for water on the bottom board, the flooding switch, detergent usage, and the drain hose. It also considers models with pressure switches or flowmeters, checking their circuits. If a real leakage is suspected, a detailed observation procedure is provided.

E6 & E7 Tree

This flowchart covers 'Open-circuit failure of thermistor' (E6) and 'Short-circuit failure of thermistor' (E7). It involves checking the NTC circuit and the Flowmeter circuit. If issues persist, replacement of the NTC is suggested.

E8 Tree

This flowchart addresses 'Diverter valve fault' (E8). It involves checking the Diverter Valve circuit. If issues persist, replacement of the NTC is suggested (note: this seems to be a general fallback in the diagram, might be a typo and should point to Diverter Valve replacement).

Caution: The real situation is unpredictable; inspection trees mentioned in this manual are for reference only.

Troubleshooting Tables

Error E1

Error E3

Error E4

Poor Washing Performance

Poor Drying Performance

Noise